Hopkins Marine Station, Stanford University, 120 Ocean View Blvd, Pacific Grove, CA, 93950-3094, USA.
Department of Biological Sciences, Macquarie University, Sydney, New South Wales, 2109, Australia.
Sci Rep. 2017 May 22;7(1):2249. doi: 10.1038/s41598-017-02402-y.
Reef coral assemblages are highly dynamic and subject to repeated disturbances, which are predicted to increase in response to climate change. Consequently there is an urgent need to improve our understanding of the mechanisms underlying different recovery scenarios. Recent work has demonstrated that reef structural complexity can facilitate coral recovery, but the mechanism remains unclear. Similarly, experiments suggest that coral larvae can distinguish between the water from healthy and degraded reefs, however, whether or not they can use these cues to navigate to healthy reefs is an open question. Here, we use a meta-analytic approach to document that coral larval swimming speeds are orders of magnitude lower than measurements of water flow both on and off reefs. Therefore, the ability of coral larvae to navigate to reefs while in the open-ocean, or to settlement sites while on reefs is extremely limited. We then show experimentally that turbulence generated by fine scale structure is required to deliver larvae to the substratum even in conditions mimicking calm back-reef flow environments. We conclude that structural complexity at a number of scales assists coral recovery by facilitating both the delivery of coral larvae to the substratum and settlement.
珊瑚礁群落是高度动态的，容易受到反复的干扰，预计这些干扰会随着气候变化而增加。因此，迫切需要提高我们对不同恢复情景背后机制的理解。最近的研究表明，珊瑚礁的结构复杂性可以促进珊瑚的恢复，但具体的机制仍不清楚。同样，实验表明，珊瑚幼虫可以区分健康和退化珊瑚礁的水，但它们是否可以利用这些线索游向健康的珊瑚礁仍然是一个悬而未决的问题。在这里，我们使用荟萃分析的方法来证明珊瑚幼虫的游动速度比在珊瑚礁内外测量的水流速度低几个数量级。因此，珊瑚幼虫在开阔海域中导航到珊瑚礁，或者在珊瑚礁上导航到定居点的能力极其有限。然后，我们通过实验表明，即使在模拟平静的后礁流环境的条件下，由细尺度结构产生的湍流也是将幼虫输送到底质所必需的。我们的结论是，在多个尺度上的结构复杂性通过促进珊瑚幼虫输送到底质和定居来帮助珊瑚礁的恢复。
